"Biomedical research has become a winner-take-all game, one with perverse incentives that entice scientists to cut corners and, in some instances, falsify data or commit other acts of misconduct," says lead author Professor Arturo Casadevallof the Albert Einstein College of Medicine of Yeshiva University, in New York.

He says the numbers stand in stark contrast to earlier studies which suggested mistakes accounted for the majority of retracted scientific papers.

Casadevall and two other scientists reviewed 2047 papers that were removed from biomedical literature through May of this year.

The authors consulted secondary sources to determine why the papers were yanked, such as the National Institutes of Health's Office of Research Integrity, and Retractionwatch.com. Both probe scientific misconduct.

They found that 21 per cent of the retractions were attributable to error, but 67 per cent stemmed from misconduct. Miscellaneous or unknown reasons accounted for the rest.

"What's troubling is that the more skilful the fraud, the less likely that it will be discovered, so there likely are more fraudulent papers out there that haven't yet been detected and retracted," writes Casadevall.

He says that earlier studies which underestimated the scope of scientific cheating were based just on journals' retraction notices, written by the original authors themselves.

"Many of those notices are wrong," he says.

"Authors commonly write, 'We regret we have to retract our paper because the work is not reproducible,' which is not exactly a lie. The work indeed was not reproducible because it was fraudulent. Researchers try to protect their labs and their reputations, and these retractions are written in such a way that you often don't know what really happened."

Prestigious journals had particularly high rates of retractions.

This reflects a prevailing culture in science in which researchers are disproportionately rewarded for publishing a lot and getting published in top-notch journals, he says.